Fluid mechanics devices

ABSTRACT

The invention provides a variety of fluid mechanics devices such as fluid-flow valves; piston and cylinder devices; fluid-flow restrictors; fluid reservoirs and fluid-flow manifolds. The devices are build up from stacks of wafer-like components. Which preferably are transparent and in each case, at least one of those components comprises an axial port and a radial port communicating with the axial port, there being concentric annular recesses in the faces of the component to receive an outer &#34;O&#34; ring type static seal between two mating components, and an inner &#34;O&#34; ring dynamic seal which acts between the wafer component and a vale rod piston rod, spindle or like device extending through the aligned axial ports of all the wafer components. Beside provide the double seal (static and dynamic) the arrangement also permits of great versatility of assembly.

The invention is concerned with fluid mechanics devices such asfluid-flow control valves; piston and cylinder devices; fluid flowrestrictors; fluid reservoirs and fluid-flow manifolds. Moreparticularly, the invention relates to fluid mechanics devices made upof or largely comprising assemblies or stacks of wafer-like components,and the invention envisages the provision of either complete devices(such as valves or piston or cylinder devices) or of kits of components(especially the wafer components) which can be assembled into suchdevices.

It is to be understood that the term "fluid" is used throughout thisspecification to include both gas and liquid, so that both pneumatic andhydraulic assemblies are envisaged. However, some of the specificembodiments which are hereinafter described are intended to be primarilyused as pneumatic devices.

In the specification of U.K. Patent No. 1 445 303, there is described afluid control valve made from a series of transparent wafer componentsassembled into a stack and held together in the stack by bolts passingthrough all the components. The device is intended to be used forteaching purposes, which is why the components are transparent, butthere is no provision for sealing between the wafer components themslves(static sealing) or between the components and the valve rod (dynamicsealing). Moreover, the components have little versatility and it isonly envisaged that they will be formed into a valve.

Specification FR 2343946 discloses a valve comprising series of wafercomponents which can be assembled into a stack and wherein in one faceof each wafer, there is an outer recess to receive a resilient ring sealfor forming a static seal between that wafer component and the oppositeface of a next adjacent wafer component, and an inner recess to receivea resilient ring seal for forming a static seal between that wafercomponent and a static valve sleeve. The wafer components also each havea mounting ring spaced from but connected to a flange in which the innerand outer recesses are formed, and the inner sealing ring of the firstwafer component engages with an end face of the mounting ring of thenext adjacent wafer component.

The present invention also employs wafer-like components, which can beassembled into a stack to produce a fluid mechanics device, but thecomponents in accordance with the invention are formed so that theyprovide any static and/or dynamic seals which will enable the device tobe used in commercial applications and at the same time, enable thecomponents to be assembled in a variety of ways, hence givingversatility to the set of components. In particular the wafer componentsare not "handed" and this facilitates assembly of the components even byunskilled persons, which makes the invention particularly useful foreducational purposes.

According to this invention a fluid mechanics device comprises aplurality of wafer components assembled into a block, in which at leasta first one of the wafer components has an axial port extending throughit from one face to the opposite face; a radial port communicating withthe axial port and extending to one edge of the wafer, and at least oneresilient ring seal forming a static seal between the first wafercomponent and a mating face of another of the wafer components in theblock, and is characterised in that there are two concentric annularrecesses in each face of the wafer, each inner recess being open on itsinside into the axial port, the two outer annular recesses being of thesame dimensions and providing alternative locations for the static ringseal, and the two inner annular recesses being of the same dimensionsand providing alternative locations for a dynamic or static resilientring seal operative between the wafer and a valve member or piston rodwhich is movable relatively to the axial port.

The first wafer component is common to all the devices which can be madeby use of the invention, some of which will be hereinafter described.Essentially, it provides a communication between two ports, one axialand one radial, but the arrangement of the two concentric recesses ineach face permits the fitting of a) static seals between the matingfaces of wafer components, and b) dynamic seals with rods sliding in theaxial port. It also permits the end of a cylinder to be located in theouter concentric recess at one side of the wafer.

In possible arrangements, the fluid mechanics device may include, inaddition to one or more first wafer components, at least one second orthird or fourth wafer component as defined below.

A second wafer component has a large axial bore extending through itfrom one face to the opposite face, and an annular recess in at leastone face of the wafer open on its inside into the large axial bore, theoutside diameter of the or each annular recess being substantially equalto the outside diameter of the outer concentric recess in the firstwafer component.

A third wafer component has an axial port of substantially the samediameter as the axial port in the first wafer component, extendingthrough the wafer from one face to the opposite face and two concentricannular recesses in each face of the wafer, of substantially the samediameters as the respective concentric recesses in the first wafercomponent, the inner recess being open on its inside into the axialport.

A fourth wafer component has an axial port of at least the same diameteras the axial port in the first wafer component, extending from one faceof the component part way only through that component, there being anannular recess of substantially the same diameter as one of the outerconcentric recess in the first component, formed only in that face ofthe wafer component where the axial port is open.

The second wafer component can be used for example threaded over acylinder with its end located in an outer concentric recess of a firstwafer component with a resilient ring fitted into and projecting from aperipheral groove in the cylinder engaging in the outer concentricrecess of the first wafer, so that the second wafer traps the projectingpart of the resilient ring and thereby secures the cylinder to the firstwafer.

The third wafer component can be used for example sandwiched between twofirst wafer components to separate their radial ports; alternatively itcan be used at the end of a stack of components to provide for thepassage of a rod through the end of the stack. The fourth wafercomponent can be used to close the end of the axial port through a stackof wafer components.

According to a preferred feature of the invention a fluid control valvemember is located in the axial port of the first wafer component. Thevalve member may comprise a valve rod or stem formed with a cut-out inone part of its periphery to provide a communicating passage when thecut-out is aligned with a dynamic seal between two radial ports, butarranged to block that dynamic seal when a full diameter part of the rodor stem is aligned with the seal, or the valve member may comprise a rodor stem formed with a tapering portion to co-operate with a small borein the device to provide a fluid flow restricter, or yet again, thevalve member may comprise a ball free to move within the axial port, butadapted to seal on a sealing ring located in one of the inner concentricrecesses.

According to a further preferred feature of the invention, thefluid-flow device may include a cylinder of such inner and outerdiameters that one of its ends locates in one of the outer concentricrecesses of the wafer components, the device including two such wafercomponents receiving respective ends of the cylinder.

It is preferred that the or at least some of the wafer components is orare transparent or translucent.

The invention also comprehends a kit comprising at least two firstcomponents; at least one of each of the second, third and fourthcomponents, at least one cylinder adapted to be located at its ends inthe outer concentric recesses of the first components and at least onevalve member.

The invention will be better understood from the following descriptionof components and fluid-flow devices which are described here by way ofexamples only, and with reference to the accompanying drawings, inwhich:

FIG. 1 is a front view of a first wafer component;

FIG. 2 is a vertical section through the first wafer component shown inFIG. 1, but also illustrating certain sealing arrangements and themanner of mounting the components;

FIG. 3 is a longitudinal section through an on/off fluid-flow controlvalve, showing first, third, and fourth wafer components;

FIG. 4 is a longitudinal section through a piston-and-cylinder deviceshowing first, second, and fourth wafer components;

FIG. 5 is a detail view to a larger scale showing the end of thecylinder of FIG. 4,

FIG. 6 is a longitudinal section through a non-return valve, and

FIG. 7 is a longitudinal section through a restrictor valve,

In FIGS. 1 and 2 there is illustrated a basic wafer component 20 whichis referred to as a first wafer component; this component being presentin all the fluid mechanics devices described hereinafter.

Essentially, the component 20 is moulded in rigid transparent plasticsmaterial and it is in the form of a square thick wafer with flatparallel faces 22 and 24. In this specific example, the component 20 is27 millimeters square and 5 millimeters thick. It will be observed thatit has: rounded corners 25; four clearance holes 26, each extendingthrough the wafer from one face to the opposite face, one clearance holebeing adjacent to each corner, and three large T-slots 28 each of whichextends through the wafer from one face to the opposite face, one T-slotopening into each of three edges of the component.

The first wafer component has a central circular axial port 30 formedthrough it from one face 22 to the opposite face 24. This axial port isan important feature of the invention, because in addition toconstituting a fluid port, it also provides a bearing housing for one ofa series of possible operating devices which will be hereinafterdescribed. An inner concentric recess 32 is formed in each face of thewafer component around the axial ports 30, and it is to be noted thatthe inside of this recess is open into the axial port 30 (see FIG. 2).In the specific example, the diameter of the axial port 30 is 5millimeters and the diameter of each inner recess 32 is 7 millimeters.An outer concentric recess 34 is formed in each face of the component 20and in the specific example, the outside diameter of each of the outerrecesses 34 is 15 millimeters. The inside diameter of each outer recess34 is only slightly greater than the outside diameter of the concentricinner recess 32, so that a narrow circular lip 36 separates the tworecesses in each face of the components; in the specific example, thislip 36 is only approximately 0.5 millimeters wide. The depth of each ofthe recesses 32 and 34 from the respective face 22 or 24 of thecomponent in the specific example is approximately 1 millimeter leavinga 3 millimeters thick portion of the wafer between opposite recesses.

The first component is completed by a radial port 38 which extends fromthe central axial port 30 to one edge of the wafer and then out througha pipe adapter 40 which extends from that edge of the wafer, the pipeadapter having three part conical sections joined end-to-end tofacilitate the securing of a flexible pipe (not shown) on its exterior.Such pipe adapters are known in various fluid-flow devices. In thespecific example the radial port has a bore of approximately 1millimeter diameter.

In order to understand how the first wafer component 20 is employed inan assembly which comprises a fluid-flow device, reference will be hadto FIG. 2, where in addition to the first wafer component 20, there isindicated the location of two further wafer components 42 and 44, thesebeing shown in chain dotted lines. As will appear hereinafter, the wafercomponents which can be used in association with the first wafercomponents are generally of the same external dimensions as the firstwafer components--though end cap components are thicker--and althoughthey vary in detail, some of these additional wafer components areformed with a central axial port of the same bore size as the centralaxial port 30 formed through the first wafer component, and with innerand outer concentric recesses around the central port, the innerrecesses opening into the central axial port, in the same way as therecess 32 in the first wafer component. For the purpose of illustrationin FIG. 2, it is assumed that the components 42 and 44 have suchconcentric annular recesses in the faces which abut face-to-face withthe faces 22 and 24 of the first wafer component 20.

In practice, the stack may comprise more than three wafer components,but in any event, all the wafer components of the stack are eventuallysecured together by bolts (not shown in FIG. 2) passing through theclearance holes 20 and engaging either with nuts, or with screw threadedinserts provided in the clearance holes 26.

A rubber "O" ring 46 is provided in each of the outer concentricrecesses 24 of the first wafer component 20. As seen in FIG. 2, this "O"ring 46 is a tight fit around the narrow lip 36, and is capable of beingreceived within the outer concentric recess 34, but the thickness of the"O" ring is such that it projects from the face 22 or 24 of the wafercomponent 20. Consequently, when the additional wafer component 42 or 44is pressed into face-to-face engagement with the face 22 or 24 of thefirst component 20, the "O" ring 46 becomes slightly compressed betweenthe bottoms of the two facing recesses 34 in the mating wafercomponents, and this produces a static seal against the egress of fluid,from the axial port passing through the centre of the stack of wafercomponents at the interface between two wafer components. The provisionof this type of static seal is important, where the fluid-flow controldevice is to be used for commercial purposes.

Also by reference to FIG. 2, it will be seen that a cylindrical rod 48extends through the axial port 30 of the first wafer component 20 andthe aligned axial ports of the additional wafer components 42 and 44.Again, the rod 48 may take various forms as will hereinafter appear. Itis a clearance fit within the central axial ports 30 of the variouscomponents. Dynamic seals for the rod 48 are formed by rubber "O" rings50 which are located in the inner concentric recesses 32. As is apparentfrom FIG. 2, each of these rings 50 projects into the axial port 30, toan extent that it is able to grip on the periphery of the rod 48,thereby forming a dynamic seal with the rod 48, because the latter isable either to slide or to turn within the "O" ring seals 50. The ringseals 50 may be contained entirely within the recess 32 of the firstcomponent 20, or as illustrated in FIG. 2, they may be contained partlywithin the recess 32 of the component 20, and partly within thecorresponding and mating recess of one of the additional components 42and 44.

It is a significant feature of the first component 20, that twoconcentric seals are provided in the concentric recesses 32 and 34.Moreover, these seals are separated by the lip 36, so that each can beconstituted by a separate "O" ring 46 or 50.

Also in FIG. 2, there is illustrated a base board 52 formed with aclearance mounting hole 54 for the reception of a hexagon headed bolt56, the head of which engages in one of the T-slots 28 of the firstcomponent 20. With the head of the bolt 56 thus engaged in one of theT-slots, and the stem of the bolt passed through the clearance hole 54,the first wafer component 20 can be secured to the base board 52, by anut 58, since when the latter is tightened on the bolt 56, the head ofthe bolt pulls the component 20 tightly into engagement with the topsurface of the board 52. It will be appreciated, that since the T-shapedslots 28 are provided in three edges of the component 20, there isflexibility for the arrangement of the component on the board 52, and inparticular, the pipe adapter 40 may be arranged to extend eithervertically upwards as illustrated in FIG. 2, or to one side, if thecomponent 20 is turned through 90° from the position illustrated in FIG.2.

It is to be understood, that similar T-slots are provided in other wafercomponents, so that the fixing bolts may be used in any of the wafercomponents, as is most convenient for securing the complete fluidmechanics device to a mounting board.

Turning now to FIG. 3, there is illustrated a fluid control valve of thegeneral kind, in which fluid enters through a port and is able to bediverted to one of two exit ports. The manner in which this is achievedusing wafer components in accordance with the invention, will appearfrom the following description.

Three first wafer components 20a, 20b and 20c are assembled into a stackin the face-to-face arrangement which has previously been described, andwith rubber "O" ring seals 46 located in the outer concentric recesses34, to form static seals between the first wafer components 20a, 20b and20c. As illustrated in FIG. 3, these first wafer components areassembled so that all their pipe adapters 40 extend from one face of thestack, but in practice, the first wafer components may be turned withrespect to each other, so that the pipe adapters project from differentfaces (e.g., the pipe adapter 38b may project from one face of thestack, with the pipe adapters 38a and 38c projecting from the oppositeface or from one of the two adjacent faces).

An additional wafer component 60 is arranged in face-to-face contactwith the first wafer component 20a, and this component 60 is of adifferent type, which is referred to herein as a third wafer component.In essence, the third wafer component is very similar to one of thewafer components 20, in that it is made of transparent plasticsmaterial, and it has the same general shape as the first wafercomponents illustrated in FIGS. 1 and 2, in particular, being formedwith the central axial port 30, and the inner and outer concentricannular recesses 32 and 34 in each of its opposite faces. Moreover, thethird wafer component 60 is formed with T-slots 28, and the clearanceholes 26. Where the wafer component 60 differs from the first wafercomponent 20, is that it is not formed with a radial port such as theport 38, nor is it provided with a pipe adapter. Consequently, unlikethe first wafer component, the component 60 is not adapted to provide acommunication between a radial and an axial port. In most instances, itwill be used in an end stack situation, such as that illustrated in FIG.3, where it is at the lefthand end of the stack of five wafercomponents.

At the righthand end of the stack of components shown in FIG. 3, thereis a fourth wafer component 70, which again, is very similar to thefirst wafer components, in that it is of the same general dimensions, itis made of transparent plastics material, and it is formed with theT-slots 28 and the clearance holes 26. However, it will be observed thatthe fourth wafer component 70 is somewhat thicker than the first andthird wafer components 20 and 60, and that the axial port 72 formed inthe component 70 does not extend completely through the component, theouter end of the port 72 being closed by a wall 74. Hence, the port 72is in the nature of a blind bore but it is somewhat larger in diameterthan the axial port 30 in the first wafer component so that there is noinner recess. Moreover, the fourth wafer component 70 is not providedwith a radial port nor with a pipe adapter such as the adapter 40 usedon the first wafer component. It is however formed with an outer annularrecess 32 in the inside face only. The outer face of the fourthcomponent 70 is quite plain and flat.

As illustrated in FIG. 3, the recessed face of the fourth component isin face-to-face contact with the first wafer component 20c, and there isa static seal between the components 20c and 70, formed by the "O" ring46.

What is not illustrated in FIG. 3 is the method of securing the fivewafer components 60, 20a, 20b, 20c and 70 together in the stack. Forthis purpose, internally threaded metal bushes are force fitted into theclearance holes 26 in the third wafer component 60, and headed screwsextend through the stack of components from the righthand end, the headsengaging with the outer righthand face of the fourth wafer component 70,and the screw threaded shanks engaging in the internally screwed bushesinserted in the third wafer component 60. It will be appreciated, thatwhen these screws are tightened, the stack is held together and thestatic sealing rings 46 are placed under compression. Also, the T-slots28 are in alignment and extend throughout the length of the stack, whichfacilitates fitting the device onto a board using bolts such as thatillustrated at 56 in FIG. 2.

The valve illustrated in FIG. 3 is completed by a valve rod 76, which isa metal rod fitted at its lefthand end with a knob 78 and at itsrighthand end with a headed rivet or screw fitted into the end of theshank 76. The head of the rivet is able to slide in the bore 72 of thecomponent 70. The outside diameter of the shank of the valve rod 76 issuch that it is a tight fit within the dynamic seals formed by the inner"O" rings 50, and therefore when it is inserted into the aligned centralports 30, it engages in the ring seals 50. Alsoi, a small metal bush 79pressed into the bore 30 of the third wafer component 60 (and with itshead located in the recess 32 on the outside of that component) acts asa slide bearing for the rod 76.

A flat 80 is milled or otherwise formed in the stem of the rod 76, andas shown in FIG. 3, when the rod 76 is at the righthand end of itspermitted motion, where it engages with the wall 74 in the fourth wafercomponent 70, this flat 80 bridges the dynamic seal 50 between thecomponents 20b and 20c. Thus, a communication is provided between theports 38b and 38c, via the inner ends of those ports, and the cut-outformed by the flat 80 in the rod 76. On the other hand, the port 38a inthe first wafer component 20a is isolated from the ports 38b and 38c, bythe dynamic seal 50 provided between the wafer components 20a and 20b,since that seal is engaging on a full circumference of the rod 76. Ifthe pipe attachment 40 appertaining to the wafer component 20b isconnected to a source of fluid under pressure, and the port 38c isconnected to a pipe leading away from the valve, then in the positionillustrated in FIG. 3, the fluid is able to flow in through the port38b, and out through the port 38c.

If the valve rod 76 is then moved to the left, until the head of therivet 77 engages with the righthand seal 50 the cut-out formed by theflat 80 in the valve rod is brought into a position where it bridges thedynamic seal 50 between the components 20a and 20b, but in thisposition, the port 38c is isolated from the other ports by the dynamicseal 50 located between the components 20b and 20c. The fluid is thenable to flow through the port 38b and out through the port 38a.Consequently, by moving the valve rod 76 between its two positions, itis possible to supply fluid from the one supply out through either ofthe outlet ports 38a and 38c.

It will be appreciated that more complicated valve arrangements can bedevised. For example, there may be more than two outlets, and indeedmore than two inlets, it being only necessary to arrange the flat orflats on the valve stem, so that by axial movement of that valve stemwithin its dynamic seals it is possible to create the necessary passageways between radial ports as required in the operation of the valve.Sliding valve rod valves are in themselves well known and it is nottherefore necessary to describe all the possible arrangements, but itwill be appreciated that by using three types of components, namely thefirst, third and fourth wafer components in various arrangements, a widevariety of valves can be provided.

FIGS. 4 and 5 illustrate a hydraulic or pneumatic piston-and-cylinderdevice. Pneumatic piston and cylinder devices are of course well knownin themselves, and the essential features of such a device areincorporated in the device illustrated in FIGS. 4 and 5. However, use ismade of some of the wafer components of the type provided by theinvention.

Referring firstly to FIG. 4, at the lefthand end of the device, there isa first wafer component 20d, which has all the features of the firstcomponent illustrated in FIGS. 1 and 2, so that it is unnecessary todescribe it in detail. At the lefthand side of the first wafer component20d, there is an additional wafer component 80, which is of a typereferred to herein as a third wafer component. Generally, theconstruction of the third wafer component 80 is identical with that ofone of the first wafer components 20, particularly in respect of itsgeneral dimensions and the provision of outer and inner concentricrecesses 34 and 32, and the third wafer component 80 only differs fromthe first wafer component 20 in that it is not provided with a radialport nor does it have the pipe connection 40 of the first component.

As illustrated in FIG. 4, there is a static seal 46 between the twocomponents 80 and 20d, and this is of the type previously described.However, in this particular instance, the third wafer component 80 actsas an end cover for a short stack of components at the lefthand end ofthe device, and consequently there are no sealing rings in theconcentric recesses 32 and 34 at the lefthand outer face of the thirdcomponent 80.

On the righthand side of the first wafer component 20d there is anotherwafer component 90 referred to as a second wafer component. Again, thishas the same external dimensions as one of the first wafer components,and is made in similar transparent plastics material. It also hasfeatures common to the other wafer components, such as the T-slots 28and the clearance holes 26. However, it is not formed with a radialport, nor does it have a pipe connector for a radial port. Moreover,instead of the relatively small diameter axial port 30 which is found inthe first wafer component 20, there is a relatively large bore 92, andat the lefthand face as seen in FIG. 4, a shallow annular recess 94,open on the inside into the large diameter bore 92, the outside diameterof the recess 94 being the same as the outside diameter of the outerconcentric recess 34 in one of the other wafer components. Thus, whenthe stack of three wafer components 80, 20d and 90 is assembled asillustrated in FIG. 4, the annular recess 94 in the fourth wafercomponent 90 is in register with the outside of the outer concentricrecess 34 at the righthand side of the first wafer component 20d.

A transparent plastics cylinder 100 is provided and this is simply inthe form of a tube, the outside diameter of which is a sliding fitwithin the large bore 92 of the second wafer component 90. At each end,the cylinder 100 is formed with a shallow peripheral groove 102 (seeFIG. 5) and a rubber "O" ring 104 is received in this groove 102, andprojects externally from the cylinder 100.

Reverting to FIG. 4, it will be seen that the end of the tube 100 fitsinto the outer recess 34 in the component 20d and the ring 104 isreceived within the shallow recess 94 in the fourth wafer component 90.Thus, when the component 90 is fitted to the component 20d, it preventsaxial motion of the cylinder 100 to the right as seen in FIG. 4, and inother words, it holds the cylinder 100 to the assembly comprising thethree components 80, 20d and 90 and it acts as a seal for the cylinder.

At the righthand end of the cylinder 100, there is a further stack ofwafer components, comprising from left to right a second wafer component90a, identical with the component 90, but turned to face in the oppositedirection, a first wafer component 20e, and an end cap in the form of afourth wafer component 70.

At the righthand end, FIG. 4 also illustrates the method by which thestacks of wafer components at each end of the cylinder are heldtogether. A countersunk headed bolt 108 received in one of the bores 26(which is correspondingly counterbored to receive the head of the bolt)extends through the stack, and there is a nut 110 on the inner end ofthis bolt. In other words, there are four such bolts and nuts at eachend of the piston-and-cylinder arrangement.

A piston rod 120 is generally of the same outside diameter as the valverod 76 illustrated in FIG. 3, so that it is able to slide in a dynamicseal provided by the "O" ring 50 between the first and third wafercomponents at the lefthand end of the cylinder. A metal bush 123 pressedinto the port 30 of the component 80 provides a slide bearing for therod 76. Also, it will be seen that the lefthand end of the piston rod120 is screw threaded at 122 so that it can be connected to an operatingmechanism. Within the cylinder 100, the righthand end of the piston rod120 is screw threaded at 124 and a plastics cylindrical piston 126 isscrewed onto this end portion of the piston rod, the lefthand end of thepiston engaging with a lock nut 128. At the righthand end, there is aslotted head screw 130 which also screws into the bore of the piston126, so that the piston is nipped between the head of the screw 130 andthe lock nut 128.

As shown in FIG. 4, the piston has a central portion of slightly largerdiameter than its main portion, but in any event, the piston itself is aclearance fit within the bore of the cylinder 100. A rubber "O" ring 132is received in a peripheral groove in the enlarged central portion ofthe piston 126, and this "O" ring 132 is a sealing fit within the boreof the cylinder 100 and acts in the manner of a conventional pistonring.

It will be appreciated, that if taking the position illustrated in FIG.4 for example, air under pressure is admitted through the radial port inthe first wafer component 20e, that air pressure is then applied to therighthand side of the piston 126, and consequently the piston is forcedto slide to the left. The air in the lefthand side of the cylinder isthen forced outwardly through the radial port in the first wafercomponent 20d, and it does not escape through the ports 30 in thecomponents 80 and 20d, because of the dynamic sealing effect of the "O"ring seal 50 which is located in the inner concentric recesses 32 ofthose two wafer components. This motion of the piston and piston rod canbe then transmitted to any other component connected to the lefthand endof the piston rod. Conversely, if air is admitted through the radialport 38 in the first wafer component 20d, then the piston will be movedtowards the righthand end. The movement of the piston is limited in onedirection by the engagement of the nut 128 with the righthand face ofthe first wafer component 20d, and in the other direction by theengagement of the head of the screw 130 with the lefthand face of thefirst component 20e.

If air is admitted alternately to each of the radial ports, then thepiston and its piston rod will be caused to reciprocate within thecylinder 100.

An interesting possibility, is to connect the piston rod 120 to thevalve rod 76 of the valve illustrated in FIG. 3, so that the totalcombination of the cylinder of FIG. 4 with the valve of FIG. 3 becomes apneumatic actuator.

In FIG. 6, there is illustrated a simple non-return valve, whichcomprises a single stack of wafer components, which from left to rightare: a fourth wafer component 70a, a first wafer component 20f, a firstwafer component 20g and fourth wafer component 70b. In general, thesewafer components are as described with reference to preceding examples,so that it is unnecessary to describe them in detail. It will be notedthat there are static seals 46 between each adjacent pair of wafercomponents.

The pipe adapter 40f forms the inlet port of the non-return valve, andis adapted to be connected to a source of air under pressure. Theadapter pipe 40g of the wafer component 20g forms the outlet of thenon-return valve, and is intended to be connected to an outlet pipe.

Within the inner concentric recesses 32 of the wafer components 40f, 40gand 70b, there are "O" rings 140 and 142, which are of rather largercross section than the "O" rings 50 used as dynamic seals. Consequently,they project further into the axial port 30 of the components.

The valve is completed by a metal ball 144 which is located in the axialport 30 of the wafer component 20g between the two "O" rings 140 and142. As will be observed from FIG. 6, the ball 144 is quite free to movewithin the port 30, and between the two rings 140 and 142. It will alsobe observed however, that it is not able to pass through the bore of oneof the rings 140 and 142.

In operation, when air under pressure is admitted through the radialport of the first wafer component 20f, it blows the ball 144 to theright, where it rests against the inside of the ring 142. The air isthen able to flow quite freely out through the radial port 38 of thefirst wafer component 20g. However, if for some reason, the air flow isreversed, air pressure will build up in the axial ports 30 of thecomponents 20g and 70b on the righthand side of the ball 144, and thiswill force the ball 144 into the position illustrated in FIG. 6, whereit rests against the ring 140, and forms a seal with that ring.Consequently, air is not permitted to flow out through the inlet port ofthe first wafer component 20f. By the simple expedient of providing the"O" rings 140 and 142 therefor, this stack of four wafer components ismade into a non-return valve.

This valve could be spring loaded, by fitting a compression springbetween the ball 144 and the end wall 74 in the righthand end component70b.

Turning now to FIG. 7, there is illustrated a fluid-flow restrictorwhich again can be produced using wafer components in accordance withthe invention. In this construction, five wafer components are assembledinto a stack, which comprises from left to right: a third component 60a;a first component 20h, a third component 60b (thicker than the thirdcomponent 60a); a first component 20j and a fourth component 70b. Sincethese components are constructed as described with reference to previousexamples, it is not necessary to describe their construction. It is tobe noted however that there are static seals provided by "O" ringsbetween the mating faces of all five wafer components. In addition,there are dynamic seals 50 provided between the first component 20h andthe components on the left hand side of that first component.

For the purpose of this construction however, a somewhat thicker "O"ring 150, is fitted in the mating inner concentric recesses 32 of thecomponents 60b and 20j. A restrictor spindle 160 made of metal, isgenerally of substantially the same diameter as the valve rod 76 shownin FIG. 3, and is received in the dynamic seals 50. In addition a metalbush 161 pressed into the port 30 in the component 60a provides ajournal bearing for the spindle. On the outside of the lefthand end ofthe assembly, a knob 162 is secured on the spindle 160. Towards itsrighthand end, the spindle 160 tapers as indicated at 164 and there isan externally screw threaded portion 166 of the spindle, which mergesinto the conical portion 164. This screw threaded portion is engaged inthe internal threads of a metal bush 168 pressed into the axial port 30of the third wafer 60b. A plastics washer 169 is located between therighthand end of the bush 168 and the sealing ring 150.

When the knob 162 is turned to rotate the spindle 160, the dynamic seals50 act as rotary seals as distinct from the sliding seals provided inrelation to the valve rod 76 in the arrangement shown in FIG. 3.However, as the spindle 160 rotates, by virtue of its screw threadedengagement in the bush 168, it moves axially, to vary the small annularspace between the outside of the tapered portion 164 and the inside ofthe washer 169.

Air under pressure flowing in through the radial port 38 in the wafercomponent 20h, can flow through the screw threaded part 166 of thespindle 160, between that part and the bush 168, and it can also flowthrough any annular space between the tapering portion 164 and the ring150, and thence out through the radial port in the first wafer component20j. However, as the spindle travels further to the right as seen inFIG. 7, the annular space between the tapering portion 164 and thewasher 169 reduces, thereby throttling or restricting the air flow,until eventually, the tapering portion 164 engages tightly with thewasher, and the restrictor is then fully closed as shown in FIG. 7.

It will be appreciated, that the devices which can be produced by use ofthe components provided by the invention are not limited to those whichhave been illustrated in the drawings. For example, an air reservoir canbe provided by a construction similar to that shown in FIG. 4, exceptingthat the piston and piston rod are omitted, and the lefthand end of theassembly is closed by a fourth component 70 in similar fashion to therighthand end.

I claim:
 1. A fluid mechanics device comprising a plurality of wafercomponents assembled into a block, in which at least a first one of thewafer components has an axial port extending through it from one face tothe opposite face; a radial port communicating with the axial port andextending to one edge of the wafer; and at least one resilient ring sealforming a static seal between the first wafer component and a matingface of another of the wafer components in the block, characterized inthat there are two concentric annular recesses in each face of thewafer, each inner recess being open on its inside into the axial port,the two outer annular recesses being of the same dimensions andproviding alternative locations for the static ring seal, and the twoinner annular recesses being of the same dimensions and providingalternative locations for a further resilient ring seal operativebetween the wafer and an axially movable actuator movable relatively tothe axial port.
 2. A fluid mechanics device according to claim 1 whereina second wafer component in the block has a large axial bore extendingthrough it from one face to the opposite face, and an annular recess ineach face of the wafer open on its inside into the large axial bore, theoutside diameter of each of the two annular recess being substantiallyequal to the outside diameter of the outer concentric recesses in thefirst wafer component.
 3. A fluid mechanics device according to claim 1or claim 2, wherein a third wafer component in the block has an axialport only of substantially the same diameter as the axial port in thefirst wafer component, extending through the wafer from one face to theopposite face and two concentric annular recesses in each face of thewafer, of substantially the same diameters as the respective concentricrecesses in the first wafer component, the inner recess being open onits inside into the axial port.
 4. A fluid mechanics device according toclaim 1 wherein a fourth wafer component in the block has an axial portextending from one face of the component part way only through thatcomponent, there being an annular recess of substantially the samediameter as one of the outer recesses in the first component formed onlyin that face of the wafer component where the axial port is open.
 5. Afluid mechanics device according to claim 1 in which the axially movableactuator is a valve rod formed with a cut-out in one part of itsperiphery to provide a communication passage when the cut-out is alignedwith a dynamic seal between the two radial ports of two wafer componentsin the block, but arranged to block that dynamic seal when a fulldiameter part of the rod is aligned with the seal.
 6. A fluid mechanicsdevice according to claim 1 in which the axially movable actuatorcomprises a rod formed with a tapering portion to co-operate with asmall bore in the device to provide a fluid-flow restrictor.
 7. A fluidmechanics device according to claim 1 or claim 4 in which the axiallymovable actuator comprises a ball free to move within the axial port,but adapted to seal on the sealing ring located in one of the innerconcentric recesses.
 8. A fluid mechanics device according to claim 1 orclaim 4 further comprising:a cylinder of such inner and outer diametersthat its ends locate in one of the outer concentric recesses of two ofthe wafer components of the block; a piston operative within thecylinder and a piston rod connected to the piston and passing throughthe axial port in at least one of the two wafer components in which theends of the cylinder are located and engaging in the seal provided bythe inner sealing ring in that wafer component.
 9. A fluid mechanicsdevice according to claim 1 in which the, or at least some of the wafercomponents is or are transparent or translucent.